To provide cellular wireless service, a wireless-service provider typically employs an access network that provides wireless connectivity to one or more access terminals (e.g., cell phones, PDAs, laptops, netbooks, tablets, and/or other wirelessly-equipped devices) located in a region. This region may be divided geographically into a number of coverage areas, such as cells and sectors, each defined by a radio-frequency (RF) radiation pattern from a respective base transceiver station (BTS). Within each coverage area, the BTS's RF-radiation pattern may provide one or more wireless links, each on a carrier (or set of carriers), over which access terminals may communicate with the access network. In turn, the access network may provide connectivity with the one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet.
The access network's wireless links may carry communications between the access network and the access terminals according to any of a variety of wireless protocols. Depending on the protocol employed, each wireless link may also be divided into a plurality of channels for carrying communications between the access network and the access terminals. For instance, each wireless link may include a plurality of forward-link channels, such as shared forward-control channels and dedicated forward-traffic channels, for carrying communications from the access network to the access terminals. Similarly, each wireless link may include a plurality of reverse-link channels, such as shared reverse-control channels and dedicated reverse-traffic channels, for carrying communications from the access terminals to the access network.
Within this arrangement, an access terminal and the access network may establish a wireless connection in various different ways. According to one example, in response to receiving an access probe (e.g., an origination message or a page-response message) from the access terminal via a shared reverse-control channel, the access network may assign dedicated forward- and reverse-traffic channels to the access terminal. In turn, the access network may transmit to the access terminal, via a shared forward-control channel, a channel-assignment message that includes identifying information for the assigned forward- and reverse-traffic channels. Additionally, the access network may begin transmitting to the access terminal, via the assigned forward-traffic channel, a series of forward null-traffic data frames.
After receiving the channel-assignment message, the access terminal may acquire the assigned forward-traffic channel and begin listening for the null-traffic data frames sent by the access network. Thereafter, if the access terminal successfully receives a given number of (e.g., two) consecutive null traffic-channel frames on the assigned forward-traffic channel, the access terminal may responsively transmit to the access network, via the assigned reverse-traffic channel, a traffic channel preamble followed by a series of reverse null-traffic data frames. In turn, if the access network successfully receives the preamble as well as a given number of (e.g., two) consecutive null traffic-channel frames on the assigned reverse-traffic channel, the access network may responsively transmit an acknowledgment to the access terminal via the forward-traffic channel. Finally, the access network and the access terminal engage in a service negotiation and then begin exchanging bearer-traffic data (e.g., voice data or packet-data) on the assigned forward and reverse channels.